The guide has been finished for a while, but I am still at it, playing CI and Impossible. So if you have any questions, just ask and you will (hopefully) be helped. Of course I'll add new helpful information, too, as I go along.

Reversely - if you find something that could help others, and hasn't properly been explored in the guide, tell me and I'll include it!

I'm doing these a little bit different to Asta, particularly on the Classic Ironman run -

Follow the Satellite Rush build order at Survival Guide (EU2012) - UFOpaedia. Implementing this strategy means selling a lot of early game resources which creates bottlenecks, but by the end of month 3 you'll have 12 satellites in the air and have all but won the game.

Start from the USA (best starting money) and cover Africa with Satellites at the end of the first month. Cashflow is critical early and Africa adds 30% to your monthly income, making the above build order significantly easier to achieve.

Leave South America without Satellites and cover everywhere else. Manage South American panic levels so you don't lose them, you can sacrifice a Euro, North American or Asian country if need be and still be fine. By leaving only South America uncovered (the bonus is the worst of all continents), you retain the ability to spawn Abduction missions, which are handy for farming resources and gaining an occasional experienced soldier as a reward. Given all abductions from that point occur on the same continent, panic levels do not rise.

On Ironman, quit to XMB if a soldier dies to keep experienced squaddies in the game. You cannot win battles within a few missions in Classic with a roster full of rookies. The autosave only kicks in after every full turn, so pay attention to the rotation and dump straight to XMB if you see a cinematic animation on an alien attack - your soldier is about to die or go critical. Backup to PS+ if need be but keep in mind you can only download a save file once every 24 hours. It's rarely necessary once you hit Lasers and Carapace tech.

Research Fragments first, then Beam Weapons, Materials and Carapace, depending on resources. Scope and Lasers makes a huge difference early in the game when you're reliant on weak weaponry and poorly trained troops. Save-scrubbing (quit to XMB) prevents death, so don't worry as much about armour until month 3.

You can delay the game indefinitely by not running the Alien Base mission. Use the time to skill up Soldiers, build your base and to research and manufacture weapons and armour. As soon as you hit Titan Armour and Plasma Rifle / Sniper / Heavy, the game becomes a cakewalk. Equip Ghost Armour and you're home and hosed. Keep in mind the enemy scales regardless, but Psionic enemies don't spawn until after the Alien Base.

Squad builds are a contentious issue, almost any choice is viable. I prefer to choose squaddie skills to maximise the number of attacks & reaction shots per round for optimal damage output.

2 x Bulletstorm attacks per round or an Attack + Overwatch compensates somewhat for the poor aim. Holo-targeting is ok for the first few missions when your squaddies can't hit the side of a bus, but is quickly redundant as troops level up.

HEAT ammo is a must against Sectopods and Cyberdisks, particularly late-game. Support troops have Suppress, get it on them instead.

5 x explosives per mission and double-damage vs robots makes the Heavy a useful squaddie. Without AOE attacks and HEAT ammo, they're all but useless.

Squadsight owns, period. Snap Shot makes the Sniper vulnerable due to their limited range. Squadsight range on the other hand is unlimited as long as you have line of sight.

Take Gunslinger so you can move and shoot in the same round, which makes up for not taking Snap Shot. It also covers your back in case of Floater jumps or close quarter battles. Pistol damage isn't bad when you hit Laser tech.

Take Battle Scanner to prevent ambushes in tight UFO spaces. Disrupting Shot is only useful for captures to whittle down HP - pistols and grenades serve the same purpose.

Double Tap for big damage on a single target or multiple kills per round. In the Zone is only useful against flanked or exposed cannon fodder which can largely be ignored, so focus the Sniper on harder enemies and the end-game instead.

Early-game, equip with Rifles. Late-game, use Plasma Rifles instead of Alloy Cannons for greater range. Scopes early, Arc Thrower mid-game, Chitin Plating late-game. Shotguns are useless at midrange, meaning you're forced into danger by closing with the enemy. On Classic Ironman, that means dead troops. I'd rather knock the enemy off before they get close enough for a Shotgun crit, hence the Rifles.

4 x attacks per round from the Assaults with a small -15 aim penalty (can effectively be offset to -5 with Scope), high critical chance and midrange attacks makes them a mean offensive combination.

Use Lightning Reflexes to trigger enemy Overwatch, Run & Gun to close within range or to flank and follow up with Rapid Fire.

Flush is useful to provide breathing room, but can force the enemy into a flanking position or surprise attack the next round. 2 x Rapid Fire attacks + Close Combat Specialist takes care of flanks and rushes instead.

Aggression and Killer Instinct become somewhat redundant late-game by wearing Ghost Armour and attacking from cloak, but the first few months are the hardest to survive, so maximise damage and aim early.

As good as they are defensively, save-scrubbing makes Tactical Sense and Resilience redundant at all times. Once you hit Lasers, it's much easier to simply kill all foes before they get the chance to retaliate.

Medkits should be the obvious choice. Equip Arc Throwers into the second slot of Supports for captures, or Scopes for 100 Aim.

The extra mobility from Sprinter is handy, but it's better to kill the enemy as fast as possible to prevent damage in the first place. Tighter formations are needed in Classic, so the extra movement is largely wasted. Save-scrubbing prevents Criticals and Deaths, so damage is boosted instead.

Some healing is necessary on every mission especially on Classic and Impossible. 6 standard Heals of 6HP should more than cover it, but often, it's cutting it close. Save-scrubbing can save some damage on a normal game, but it's better to have a 10 point heal on hand in Ironman nearing the mid-game than wasting time on a reboot.

Think of Support as the defensive counter to Assault. Pin down the enemy with 2 x Suppression or 2 x Overwatch Reaction Shots to cover Assaults and to take out lighter enemies. Suppression may trigger Grenade throws, so give your squad some spread. Oftentimes, Suppressed enemies skip their turn making for an easy kill on your next round.

If you have PlayStation®Plus, you can upload your Ironman save game (even though it is protected) to your Online Storage - but you have to wait 24 hours until you can download it again. So if you upload the save game at the start of each mission, you can retry it the next day if you really screw up.

In my Ironman classic playthrough, I played the first five missons before I had PlayStation®Plus (only one soldier was hit one time ). Then I boutght PlayStation®Plus and I can tell you, I played a lot more relaxed after that - still playing very carefully, because you really don't want to wait 24 hours to retry a mission. And I was really glad to have a backup, when I lost the whole team in the first terror mission!

Of course, you must not turn on the auto save game upload feature for XCOM

Just wanted to leave a tip for those who may be having problems getting the Ride of the Valkyries trophy to pop. It isn't glitched, per se, but you do have to avoid using Mind Control on any enemies. Apparently, any mind-controlled aliens count as a male member of your team. I found out the hard way after completing a difficult mission (3 of my ladies were gravely wounded) and getting no trophy. I did it a second time without using any psi-abilities, and the trophy popped soon after. Good luck!

The easiest way to get Ride of the Valkyries is to just do it on the 2nd mission of a new Normal, or Easy difficulty, game. Play the first one with the team that you get and switch in enough women for the 2nd one. No need to wait until you're fighting anything harder than Sectoids and Thin Men.

I will not accept blank friend requests.
Also if English is your native language and you write/speak like you're retarded, I will probably ignore you.